Impact of transcranial Doppler on the management of delayed cerebral ischemia: a propensity-matched analysis

Vasospasm following aneurysmal subarachnoid hemorrhage (aSAH) is typically diagnosed using CT or catheter angiography, both of which involve radiation exposure, iodinated contrast agent administration, and the transfer of critically unwell patients to the radiology department. Transcranial Doppler (TCD) ultrasound offers a bedside radiation-free alternative, but concerns regarding diagnostic performance have limited widespread use. The aim of this study was to assess whether routine TCD monitoring in patients with aSAH influenced the incidence of delayed cerebral ischemia (DCI) and long-term functional outcomes.

This retrospective single-institution study analyzed patients who were treated for aSAH before (2019-2020) and after (2021-2022) the introduction of routine TCD monitoring. Clinicodemographic data were analyzed, with propensity score matching and multivariable regression used to control for confounders. The primary outcome was the modified Rankin Scale (mRS) score at 6 months, with DCI incidence as a secondary outcome.

Of 466 patients (305 female, mean age 56.6 years) included in this analysis, 239 were in the pre-TCD group and 227 were in the post-TCD group. Baseline demographics and comorbidities were similar between the groups, as was the 6-month favorable functional outcome (mRS scores 0-2; 74.5% vs 73.6%, p = 0.906). However, following propensity score matching, routine TCD monitoring was found to be associated with reduced odds of poor outcome (matched OR 0.50, p = 0.010). The incidence of DCI was lower in the post-TCD cohort (18.1% vs 25.5%) and multivariable analysis confirmed a protective effect of routine TCD monitoring on the incidence of DCI (OR 0.48, p = 0.004). Counterfactual analysis indicated an absolute risk reduction for clinical DCI of 5.3% (p = 0.026) and relative risk reduction of 18.7% in association with the use of TCD.

The implementation of routine TCD monitoring was associated with improved functional outcomes and a reduced incidence of DCI in patients with aSAH. These findings support routine TCD use for early vasospasm detection and timely intervention, but require prospective multicenter validation.